For what it’s worth, I was a less extreme version of your boyfriend during my first real relationship. I was very fragile and while my girlfriend didn’t need to tickle my mustache, I would be very obsessive about things being “right”. After the relationship broke down, I finally realised wow, I’m choosing to be this way by not addressing my issues so I started addressing my mental health issues. I’m now medicated and I have very normal relationships (my most recent was the polar opposite of my first) and when I reflect on my first relationship, I realise how disrespectful of me it was to expect my girlfriend to tolerate such behaviour.

I can’t diagnose your boyfriend, but I am confident in saying that it’s his responsibility to tackle his problems and while you can choose to stay and support him in that journey — relationships can involve sacrifice! — it’s completely unreasonable for you to be expected (by him or yourself) to stay with someone who is choosing not to address their issues.

Please break up with him if he doesn't get help, he's unwell and it's unfair for your happiness to be dragged down with him.